from selenium import webdriver
driver = webdriver.Firefox()
driver.get('https://mail.163.com/register/index.htm?from=163navi&regPage=163')
#1. 通过id
driver.find_element_by_id('username').send_keys('yxd')
driver.find_element_by_id('password').send_keys('yxd')
driver.find_element_by_id('phone').send_keys('yxd')
#2. 通过classname
driver.find_element_by_class_name('custom-checkbox service').click()
#3. 通过CSS选择器
driver.find_element_by_css_selector('body > div.register-container > div > div > div.m-body > div.register-option > a.j-register').click()
#4. 通过Xpath
driver.find_element_by_xpath('/html/body/div[2]/div/div/div[1]/a').click()
#5. 通过name  
driver.find_element_by_name()
#6. 通过tag   
driver.find_element_by_tag_name()
#7. 通过超链接 全名
driver.find_element_by_link_text('javascript:').click()
#8. 通过超链接 部分
driver.find_element_by_partial_link_text('script:').click()